1. Field of the Invention
This invention relates to a gas cooking apparatus with a rotary burner and electrical ignition.
Gastronomy demands that cooking of certain culinary preparations be obtained with a very low heat flow over a rather long period, or on the contrary, with a rather high heat flow over a rather short period, in order to obtain a very fast change in the corresponding preparation.
In order to solve the problems posed in the first case, gas cooking apparatus are generally fitted with a special burner, small in diameter, having therefore a small number of nozzles. However, if by means of this device, heat flow can be very much reduced, this flow is however limited to a small part only of the vessel bottom; thus there is a much faster transformation of materials in this area, near the bottom, that can bring about some local carbonization, which changes the taste of the preparation.
In the second case, the specific heat and the thermal conductivity of the mix that makes up the preparation, cause a temperature difference between the bottom and the upper part, producing a time gap in the transformation processes wanted between bottom and surface; which, in this case also, can cause an overheating of the materials that are near the bottom, and this overheating can produce: thickening, unwanted coloration, sticking to the bottom of the container, and, as an extreme effect, some carbonization modifying the taste, even to the point of making the preparation unfit for consumption.
In order to obviate these drawbacks, one would use traditionally, depending on the case, a heat spreader that was placed between the burner and the container bottom, or a simple water bath or one combined with an agitator, when cooking had to be run in a very progressive manner and when the preparation consistency allowed it, or a "hand trick" combining an alternating movement of the container held with one hand, above the burner, with agitation of the preparation with a spatula, in order to homogenize the mix transformation.
In order to remedy this situation and enable amateur cooks to achieve culinary preparations requiring somewhat delicate cooking, some manufacturers had the idea of fitting gas cooking devices with a rotary burner generating a rotating heat flow, with the aim to obtain a more regular and more homogeneous preparation.
2. Background Art
The state of technology is represented by devices described in the following patents:
U.S. Pat. No. 2,646,788, of which the object is a rotary burner made of a rotating gas bar, with a length corresponding to the maximum diameter of containers to be heated, with upward nozzles, evenly spaced, from the center towards the ends.
With such a burner, gas outlet nozzles can be easily obstructed, during an overflow, and the heat flow is larger around the center than at the periphery; this could only be imperfectly compensated by an irregular distribution of the nozzles, and/or by some progressivity in the nozzle diameter, from the center towards the ends of the bar. Besides, gas cooking apparatus as they are marketed today, are generally fitted with an electrical ignition device that would be rather difficult to combine with a rotary burner with rotating bar, and with outlet nozzles looking upwards, because the igniter would need, in this case, to be placed in the space left free between this bar and the bottom of the container.
French Patent No. 2.499.220 concerning a gas cooking apparatus, fitted with a rotating circular burner carrier, supporting a small off-center burner of wich the circular path is situated close to a fixed igniter. The burner carrier includes a chamber communicating with a tapered duct, making a venturi nozzle, installed in the drive shaft, the lower end of which communicates with a fixed chamber that includes, on its sides, the air inlets and, on the centerline, a gas inlet duct. The drive shaft of the burner carrier includes a collar fitted with an index finger allowing the burner orientation to be made to coincide with that of the burner on stoppage, in order to enable later electrical re-ignition to be made. With such an arrangement, the heat flow is much better spread than with the rotating bar burner examined hereabove. However this result is obtained through a combination of means relatively complex, which present certain drawbacks the main ones of which reside in the need for a rather accurate alignment of the rotating burner in relation to the fixed burner, and for a proper tightness between the lower end of the driving shaft and the mixing chamber, in an overall height incompatible with the incorporation with a heating plate in an integrated cooker, and in a bad combustion index resulting in a reduced efficiency and production of carbon monoxide.